Isn't the whole point with PWA the transition from traditional web applications into a more native like world for the web platform? The end user should preferribly not notice that they are actually using one or the other.
One of the corner pillars of PWA is the notion of offline first. The user shouldn't be welcomed with an offline screen but rather with a hydrated application. Then the question becomes which parts of the application should work and how much data should be stored on the client. But that is another discussion.
So just discarding PWA, and specifically offline functionallity, with the argument that the main purpose of forums are engagement and interaction seems a bit weird.
Just my 2 cents.
Kind regards,
